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I have 2 V570's that i would like to setup to mirror each other.

i have 1 setup with 2 modbus ports (1 & 2)

port 1 is connected to a PC via modbus as slave

port 2 is connected to another V570 Via modbus as master

the second PLC is setup with port 2 as slave

I'm to receive data from the pc and have both PLC's make changes to the data and send it back to the pc


the first PLC is getting MI 100 - MI 132 and MI 200 - MI 232 and MI 1000 - MI 1045 from the PC and sending the data to the second PLC at the same MI addresses


the second PLC is receiving the same MI's from the first PLC and sending the same MI's back


the problem I'm having is the PLC'S are sending the same data back and forth before i can make my changes to the data.


is there another way of mirroring the two PLC'S together?

test slave.vlptest master.vlp

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  • MVP 2023

Mirroring in three masters is not as easy as it looks, as you've discovered.  I use the term "master" because each device is capable of changing the data.


You're going to have to add a timer and some handshake bits to slow down the transmissions.  Where is the real data located? In the first V570?  Can the second V570 change the data, too?


Please clarify your data flow a bit.


Joe T.

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I'm not sure if I'm going about this the right way but what i would like to do is have both V570 able to make changes to the data from the PC. the idea is to have one V570 on each end of the room and if i make a change on one V570 the change will go to the other V570 and the PC.


i have the first V570 reading data from the PC and also sending the same data to the second V570

the second V570 is sending the same data back to the first V570

both V570's have the same program in them other then the modbus setting


the data flow is

MI 100-MI 132 data going to the PC (PC Inputs)

MI 200-MI 232 data coming from the PC (PC output)

MI 1000-MI 1045 string data coming from the PC (PC Output - Read only)


thanks for your time,

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